A rotary damper used in the related art includes a shaft, a pair of side panels that support the shaft rotatably, a case that is sandwiched between the pair of side panels such that an operating chamber is defined in an interior thereof, and a vane provided on the shaft so as to divide the operating chamber into a first chamber and a second chamber.
JP11-82593A and JP11-344066A, for example, disclose rotary dampers that operate when an external rotary force is exerted on the shaft, whereby the vane moves within the operating chamber in response to the rotation of the shaft, causing the first chamber to contract and the second chamber to expand. In these rotary dampers, a damping valve applies resistance to a flow of oil moving from the contracting first chamber to the expanding second chamber, and as a result, the rotation of the shaft is damped.